Robert Osfield wrote:
> Hi Chris,
> I have just reviewed the your suffix change and I'm not sure I quite
> get why you need it.

  This code is to support additional functionality that I haven't yet been 
permitted to
release, but I expect to soon.

> The PagedLOD's DatabasePath member is required to make sure that path
> that a tile is loaded from at runtime it recorded so that it's
> children can be found, this DatabasePath is set on load of the node so
> is actively used.
> This contrasts your new DatabaseSuffix change, it's not recorded or
> set anywhere in the OSG, so I can only assume it's your app that is
> setting, and if so then why not just append the suffix to the
> childrens filenames directly?  Also if this appending of the suffix is
> something done dynamically then the route I would take is to write a
> custom Registry::ReadFileCallback that intercepts all readNodeFile()
> etc calls and then adds the suffix there.  Such a callback avoids the
> need to modify the scene graph at all so will be easier to implement
> and more more efficient.
> Given that I feel that your changes tackle a problem in way that I
> would recommend I don't feel it's appropriate to merge them as they
> just add complexity to the implementation for little or no value add,
> and in fact may just confuse users into tackle things in a less
> optimal way.

  The non-persistent suffix is there to support propagation of a pseudoloader 
suffix
throughout the process of loading a PagedLOD database, without persistently 
altering the
structure or filenames of the resulting database once it is loaded. This way it 
can be
re-saved with the modifications caused by the pseudo-loader, but without any 
permanent
alteration to the filename structure of the database. This is needed because if 
you apply
a pseudoloader to the top-level PagedLOD scenegraph file, the filenames 
embedded in the
PagedLOD nodes' perRangeLists don't automatically inherit this.

  I have a visitor that appplies this suffix to the PagedLODs automatically, 
but it needs
to do it without permanently tainting the perRangeList child filenames -- thus 
the
emphemeral suffix which isn't saved.

  You and I discussed the terrain-modification approach this summer and the 
pseudoloader
technique was your own suggestion.

  I don't believe the ReadFileCallback is a safe way to integrate with the 
pseudoloader.

> Robert.

-- 
Chris 'Xenon' Hanson, omo sanza lettere                  Xenon AlphaPixel.com
PixelSense Landsat processing now available! http://www.alphapixel.com/demos/
"There is no Truth. There is only Perception. To Perceive is to Exist." - Xen
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